Linguistic Invariants and Language Variation

Since the publication of Noam Chomsky’s field founding Syntactic Structures in 1957, generative grammarians have been formulating and studying the grammars of particular languages to extract from them what is general across languages. The idea is that properties which all languages have will give us some insight into the nature of mind. A widely acknowledged problem to which this work has led is how to reconcile the goal of generalization with language specific phenomena and the cross language variation they induce. Good science requires that cross linguistically valid generalizations be based on accurate, precise and thorough descriptions of particular languages. But such work on any given language increasingly leads us to describe language specific phenomena: irregular verbs, exceptions to paradigms, lexically conditioned rules, etc. So this work and cross language generalization seem to pull in opposite directions. Here we propose an approach in which these two forces are reconciled. Our solution, presented in greater depth in Bare Grammar (Keenan and Stabler, 2003), is built on the notion of linguistic invariant. On our approach different languages do have non-trivially different grammars: their grammatical categories are defined internal to the language and may fail to be comparable to ones used for other languages. Their rules, ways of building complex expressions from simpler ones, may also fail to be isomorphic across languages. So languages differ. Nonetheless certain properties and relations may be invariant in all natural language grammars, as we will see below. And it is to these linguistic invariants that we should look for properties of mind. Our approach contrasts with that of the most widely adopted linguistic theories, where the dominant idea is that there is only one grammar, the grammars of particular languages being, somehow, special cases. This has led to a mode of description in which grammars of particular languages are given in a notationally uniform way: the grammatical categories of all languages are drawn from a fixed universal set, as are the rules characterizing complex expressions in terms of their components. It has also led to the postulation of a level of unobservable structure (“LF”, suggesting